A hard coating film has been used for protecting the surface of various image displays including a liquid crystal display device (LCD), an electroluminescence (EL) display device, a plasma display (PD), a field emission display (FED) and the like.
Recently, a flexible display which can maintain display performance even when it is bent like a paper by using a flexible material such as plastic, instead of a conventional glass substrate having no flexibility, gains attention as a next generation display device. In this regard, there is a need for a hard coating film which not only has high hardness and good impact resistance but also has proper flexibility, without curling at the film edges during its production or use.
Korean Patent Application Publication No. 10-2012-0078457 discloses a hard coating composition which comprises an impact modifier, a photopolymerizable compound and a photo-polymerization initiator, wherein the impact modifier includes a rubber core and one or more shell layers. It is described that a hard coating film to which the hard coating composition is applied can implement excellent scratch resistance, film adhesion, impact resistance, solvent resistance, processability, flexibility, etc.
However, such a hard coating film has a problem that it is difficult to secure impact resistance and bending resistance while having sufficient hardness and flexibility to be applied to a flexible display device.